Numerical Modeling of Grout Injection for Hybrid Bored Prestressed Concrete Cased Piles

In this paper, a numerical analysis of grout flow in a narrow 10-mm soil-pile gap was conducted using the ANSYS Fluent software. The Volume of Flow (VOF) method was used to model the grout flow through the soil-pile gap. Two-phase transient flow simulations were carried out with grout and air being the two immiscible fluids. Four different pile diameters of 800, 1000, 120,0 and 1400 mm were considered and for each pile diameter, grouts with two different water-cement ratios of 0.4 and 0.5 were pumped into the soil-pile gap. Numerical results indicate that: (1) for the same pile diameter and grout pressure, the height of grout flow increases as the water-cement ratio increases from 0.4 to 0.5; (2) for the same grout pressure, the height of grout flow decreases as the pile diameter increases; (3) for a give pile diameter and water-cement ratio, the final grout height is mainly dependent on the grout pressure but insensitive to the inlet configuration; and (4) the two-inlet configuration is more effective in eliminating entrapped air at the bottom of the pile than the three- and four-inlet configurations.